1. Field of the Invention
The present invention relates to a driving device for a heating roller of an image forming apparatus and, more particularly, to a driving device for a heating roller of an image forming apparatus in which the heating roller is moved to contact or separate from a photosensitive belt by a single motor.
2. Description of the Related Art
In general, an image forming apparatus which reproduces images of text and/or pictures on a recording medium according to transmitted image data signals is provided with a photosensitive member such as a photosensitive drum or a photosensitive belt for forming an electrostatic latent image thereon, a charging device for charging the surface of the photosensitive member, an exposure device for forming an electrostatic latent image of a predetermined pattern by illuminating the charged surface of the photosensitive member with a light beam, a developing device for developing the electrostatic latent image by applying a developing agent such as developer liquid or a toner to the exposed latent electrostatic image, and a transfer device for transferring the developed image to a recording medium.
FIG. 1 shows a schematic diagram illustrating the structure of a conventional image forming apparatus.
Referring to FIG. 1, the image forming apparatus comprises a photosensitive belt 104 to circulate around first, second and third belt rollers 101, 102 and 103, a discharging device 105 for removing any charge remaining on the photosensitive belt 104, and a charging device 106 for charging the surface of the photosensitive belt 104. Exposure devices 107, 108, 109 and 110 having respective laser scanning units (not shown) are provided for illuminating an imaging region of the charged photosensitive belt 104 to selectively remove charge in the shape of an image by respective laser beams in order to form an electrostatic latent image. Developing devices 111, 112, 113 and 114 are provided for developing the electrostatic latent image by applying a developer liquid. A drying device 115 is provided for drying the developer liquid applied to the latent image, and a transfer device 116 is provided for transferring an image developed on the photosensitive belt 104 to a recording medium 117 such as a paper sheet or a film frame.
In this case, the developing device 111 comprises a developing roller 111a for applying the developer liquid to the photosensitive belt 104, a developer liquid supplying device 111b for supplying the developer liquid to the developing roller 111a, a cleaning roller 111c for removing the developer liquid adhering to the rear surface portion of the developing roller 111a, first and second squeegee rollers 111d and 111e for removing excess developer liquid from the photosensitive belt 104, first and second blades 111f and 111g for removing the developer liquid adhering to the first and second squeegee rollers 111d and 111e, and a developer liquid recovery container 111h for recovering the developer liquid within the apparatus. In addition, the drying device 115 is provided with a heating roller 115h for drying the developer liquid adhering to the photosensitive belt 104, and the transfer device 116 comprises a transfer roller 116t for transferring an image from the photosensitive belt 104 to a recording paper by relatively rotating in contact with the first belt roller 101 with the photosensitive belt 104 interposed therebetween, and a pressure roller 116p for fixing the image transferred on the transfer roller 116t onto the recording paper by relatively rotating in contact with the transfer roller 116t with the recording paper interposed therebetween.
On the other hand, in the conventional image forming apparatus constructed as described above, the drying device 115 is provided with auxiliary rollers 115r and 115s in addition to the heating roller 115h, as shown in FIG. 2. The auxiliary rollers 115r and 115s remove the liquid toner remaining on the heating roller 115h, and also a voltage higher than a development voltage of the photosensitive belt 104 is applied to the heating roller 115h via the auxiliary rollers 115r and 115s to prevent the liquid toner on the photosensitive belt 104 from adhering to the surface of the heating roller 115h.
In the drying device 115 as described above, while the image forming apparatus is in an operating state, the heating roller 115h is caused to contact the photosensitive belt 104 in order to remove the remaining liquid toner on the photosensitive belt 104, and while the image forming apparatus is not in the operating state, the heating roller 115h is caused to separate from the photosensitive belt 104. Conventionally, the contacting and separating movements of the heating roller 115h are performed by two respective driving motors 203 and 204. Therefore, the structure of the apparatus is complicated, and the manufacturing cost of the apparatus is high because two motors 203 and 204 are used. In FIG. 2, reference numeral 201 denotes a main controller which commands the operations of the two motors 203 and 204, and reference numeral 202 denotes a motor controller which controls the operation of the motors 203 and 204 corresponding to the command from the main controller 201.